Spark plug shield



March 8, 1949. P, 5 VAN QRDEN 2,463,924

SPARK PLUG SHIELD Filed May 9, 1946 ININ'I'OR.

CLLILS.VOJI Orderl Patented Mar. 8, 1949 SPARK PLUG SHIELD Paul S. Van Orden, Stirling, N. J., assignor to Breeze Corporations, Inc., Newark, N. J a corporation of New Jersey Application May 9, 1946, Serial No. 668,605

4 Claims.

This invention relates to spark plug shields such as are used to prevent the radiation of electrical waves from ignition systems. Such radiations interfere with radio communication with aeroplanes, ships, or vehicles using internal combustion engines.

An object of this invention is to supply an effective shield which may be readily used in conjunction with a typical aviation type spark plug.

Another object of this invention is to construct a spark plug shield which is adapted for use where the spark plug is located in a deep recess or well in the cylinder head.

A feature of this shield is that it may be easily and quickly applied or removed.

Another feature of this shield is that it may be inserted upon or taken off the spark plug without removing the said plug.

An object of this shield is to form a closed chamber around the stem of the spark plug to prevent water, oil, or other foreign substances from entering therein.

Another object of this invention is to furnish a shield which will withstand shocks and vibrations, having an internal insulator which may be easily replaced in the field.

The invention consists of the construction, combination and arrangement of parts, as hereinafter illustrated, described and claimed.

In the accompanying drawings, forming part hereof, is illustrated one form of embodiment of the invention, in which drawings similar reference characters designate corresponding parts, and in which:

Figure 1 is a vertical section of a complete embodiment of the spark plug shield with the contact portion cut away.

Figure 2 is a side elevation of the body portion of the shield shell.

Figure 3 is a horizontal section, taken on line 33 of Figure 2.

Figure 4 is a vertical section of the outlet housing of the shield.

Figure 5 is a vertical section of the dielectric shield liner.

Figure 6 is a side elevation of the ring retainer of the spark plug shield.

Referring to the drawings, and particularly to Figure 1, l0 indicates a cylindrical metal shell body. The upper end of the shell I0 is sealed by a dome shaped structure ll integral therewith. The lower portion of the shell I0 is open and expanded into a hollow hexagonal shape l2. The inside dimensions of the expanded portion of the 2 shell l2 permits it to slide snugly over the hexagonal member M of a typical aviation spark plug I5. The bottom of the shield l0 rests upon the circular flange I3 of the spark plug 15 and grounds the shield to the plug at that point.

A series of horizontal slots l'l, shown in Figure 2, is cut into the hexagon-shaped base. Each slot I! is sufficiently deep to cut through the corners l8 of the hexagonal shape l2 for a hereinafter described purpose. The shell ID is provided with a hole l9 adapted to receive an ignition lead cable 20 which is connected to the spark plug iii.

The ignition cable 20 is passed through an outlet 2| before it enters the shell ID. The outlet 26 is attached, as by soldering, to the shell iii and shields the openings l9 therein. The outlet M is tubular in shape and is provided with an external thread 22 at the end thereof for attachment of a shielded conduit 23.

A flexible insulating lining 24 hereinafter referred to as rubber, but not limited to that material, is inserted within the shield. The insulator 24, as shown in Figure 5,-comprises a hollow main body portion 25, which conforms to the shape of the shield shell I0, and an extending sleeve 26 integral therewith which projects into the bore of the outlet 2 I. The lower portion of the main body 25 of the insulator terminates in a thinned rim 2'! having an inner chamfer 28. This construction of the insulator 24 serves a twofold purpose. When the shield is applied to the spark plug IS the thinned rim 2'! bears firmly against the metal of the plug IE to seal the'chamber within the shield. In addition, the insulator 24 is compressed between the shield l0 and the spark plug l5, cushioning the shield against any vibrations or shocks which might be transmitted to it from the engine.

A snap ring 29, shown in Figure 6, completes the construction of the spark plug shield. The ring 29 is sprung apart and slipped into the slots IT in the hexagonal portion l2 of the shield body Hi. When the shield is applied to the spark plug IS the ends 30 of the snap ring 29 are pushed apart slightly by a screw driver or other tool and the assembly pressed downward. As the snap ring 29 reaches the bottom of the hexagonal member H of the spark plug l5 it snaps into the groove 3| provided at that point on this type of spark plug, and grounds the shield to the plug [5.

The shield is prevented from moving downward under the efiects of vibration by reason of its resting on the spark plug flange IS. The snap ring prohibits the accidental withdrawal or removal of the shield by grasping the plug l5, as

previously described.

member I4 by withdrawing the assembly.

The rubber insulator 24 may be extracted from the shield for replacement by pulling it through the opening in the body portion 10 of the shell. To replace the insulator 24 it is only necessary to bend the sleeve portion 26 upward, compress the rubber body portion 25 and push it into position. The sleeve member 26 is guided into the outlet 2| until the insulator assumes the position shown in Figure 1.

In the preferred embodiment of the invention, the outlet 2| is provided with an internal taper 32 at its outer end. A compressible washer 33, hav-- ing a frustro-conical shape, surrounds the ignition cable 20 and is seated within this taper 32. When the ignition cable 20 is inserted into the outlet 2| and the coupling nut 34 on the ignition conduit 23 is tightened on the thread 22 of the outlet 2 I, it forces the contact 37 against the electrode terminal 38 of the plug i and squeezes the washer 33 between the conduit ferrule 35 and the taper 32. This pressure forces the washer 33 into the insulation 36 of the ignition cable 20, forming a seal at this end of the spark plug shield.

It is clear, from an examination of Figure 1, that the volume of air about the plug is small as compared to prior types of shield. The condensation of water-vapor within the chamber when the plug cools is therefore kept at a minimum. The construction and use of the rubber insulator 24 permits of the small chamber around the plug while providing adequate radio shielding.

The use of this shield in the field without recourse to special tools is aided by the ceramic sleeve 39 which is slipped over the contact end of the ignition cable 20. This sleeve 39 is provided with a pierced wall 40 integral therewith and spaced from the front end thereof. A hollow rivet 4| is peened over within the bore of the sleeve wall 40 and a contact spring 31 engaged upon a flange 42 of said rivet M. This assembly is applied to the ignition wire 43 by the simple expedient of stripping the insulation 36 from the end of the cable, passing the exposed wire through the central bore 44 of the rivet 4| and flaring the strands of the wire 43 outwardly and back upon the head of the rivet 40. The assem bled terminal may now be slipped into the outlet sleeve 26 of the spark plug shield.

The small amount of clearance required by the locking device on this shield makes it especially adaptable for use on engines where the plug is placed within a deep recess or wall within the cylinder head. The shape of the retaining ring 29 makes it possible to quickly release it and re- In order to remove the shield, it is merely necessary to spring the ends- 30 of the ring 29, and slip it over the hexagonal am-m move the shield by using a screw driver-or. other ,tool. This operation, too, may 'be" 1 a constricted space. g

Having thus fully described the'inventl0n,;whatj is claimed'as new and desired toibejsecuredby Letters Patent of the United Statea is:

1. In a spark plug shield, a metal shield body closed at its upper end and having its open end formed into a hexagonal shape, each corner of which is provided with a horizontal slot piercing said corners and spaced from the end therebf, a metal lateral outlet thereon and a snap ring embracing the said shield and insertable within the said slots to lock the shield to a spark plug.

2. In a spark plug shield, a metal shield body closed at its upper end and having its open end formed into a hexagonal shape, each corner of which is provided with a horizontal slot piercing said corners and spaced from the end thereof, a metal lateral outlet thereon having an external thread and an internal taper on the outer end thereof and a snap ring insertable within the said slots to lock the shield to a spark plug.

3. In a spark plug shield, a metal shield body closed at its upper end and having its open end formed into a hexagonal shape, a hollow dielectric member provided with a thinned rim and an internal chamfer at the lower end thereof, disposed within and conforming to the shape of the said shield and outlet and a snap ring embracing the said shield and adapted to lock the shield to a spark plug.

4. In a spark plug shield, a metal shield body closed at its upper end and having its open end formed into a hexagonal shape each corner of which is provided with a horizontal slot piercing the said corners and spaced from the end thereof, having an external thread and an internal taper on the outer end thereof, a hollow dielectric member disposed within and conforming to the shape of the said shield and outlet and a snap ring embracing the shield and insertable within the said slots to lock the shield to the spark plug.

PAUL S. VAN ORDEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 891,112 Stuart June 16, 1908 1,503,692 McCarthy Aug. 5, 1924 1,806,548 Rabezzana May 19, 1931 2,320,044 Merriman May 25, 1943 2,352,481 I-Iyland June 27, 1944 2,355,116 Shumaker Aug. 8, 1944 nor ed in j j p 

